high voltage on genset

i have a fg wilson genset max power output 15 kw connected to an offgrid SMA solar power system 16 kw capacity, there is two 8 kw inverters connected together.
the generator is used to charge 24 lead carbon batteries on days with limited sun
the system has worked without problems for 4 years, a few months ago the generator went over voltage, set usually at 240 volts 50 htz ,
went to 320 volts
i checked all connections and replaced the genset voltage regulator, and the fault still occurs intermittently
any ideas where to look next
 
A single line diagram would be welcome to start to support from here

Also a drawing or document showing load balance would be nice

Is the load charge is varying /fluctuating during the charging of the 24 lead carbon batteries ?
 
this is the wiring diagram. the voltage in the genset is controlled by the avr and can be adjusted by turning the pot , the khz is controlled by the engine speed , so the engine speed under load is set to 50khz, when no load the engine revs are slightly higher, a usual reading is 52.5 khz
i have 2 sunny island inverters, they control the power from the solar panels and genset to the batteries

Connecting the generator to a Single Phase Single Cluster System
In a single phase operation with multiple Sunny Islands i.e. one, two or three phase setup, the generator connections need to be paralleled to the second and third Sunny Island in order to get power from the generator of approximately 11.5kW per Sunny Island. In single—phase single-cluster systems, the Sunny Island inverters must be of device type SI6.0H-11 or SI8.0H-11.

Circuitry Overview: Single-phase Single-cluster System
Circuitry Overview: Single-phase Single-cluster System
 
Thank you for sharing SLD and other informations

Did you monitored the frequency at output of Genset ?

If yes , do you see any abnormal deviations?

Well the installation seems to be an off grid (islanded systems ) it will take some times to find the cause of the issue

Can you tell us more on the AC loads ...( nature , consumers ...)
 
Thanks for the reply,
The AC loads vary the a/c unit for the house is the largest draw , we can run a/c oven and hotplates together, the house is well under the capacity of the system. i run the workshop lathe, milling machine, power saw and welders through a single phase to 3 phase digital inverter, this is only turned on when i use the machines, i checked it was not on when the problem arose because it has some very big capacitors to help start the machines. The problem is the generator changes voltage when charging the batteries through the island inverter. there is a read out on the generator, when the circuit breaker is opened that goes to the inverter the over voltage at the genset still exist, yesterday i set genset at 240 volts ran for an hour then inverter disconnected automatically because the voltage had gone to 250 volts at the generator
 
Thanks for the reply,
The AC loads vary the a/c unit for the house is the largest draw , we can run a/c oven and hotplates together, the house is well under the capacity of the system. i run the workshop lathe, milling machine, power saw and welders through a single phase to 3 phase digital inverter, this is only turned on when i use the machines, i checked it was not on when the problem arose because it has some very big capacitors to help start the machines. The problem is the generator changes voltage when charging the batteries through the island inverter. there is a read out on the generator, when the circuit breaker is opened that goes to the inverter the over voltage at the genset still exist, yesterday i set genset at 240 volts ran for an hour then inverter disconnected automatically because the voltage had gone to 250 volts at the generator
Thanks for the reply,

Are you saying that overvoltage occuring even generator circuit breaker is open

We need some datas like AC load behavior , Genset Output Amps, Voltage , HZ , RPM, to give a better support
 
the genset is rated at 15 kw its single phase 240 volts 50 hz rpm 1500 when under load , the parameters set in the solar inverter limit to 25 amps draw from the genset, the overvoltage occurs at genset only when under load, charging the 24 off 2 volt batteries through the inverter.
if i open the circuit breaker at the genset the readout at the genset stays at the high voltage until i adjust the avr
this why i suspected the avr was faulty and replaced it
i think the solar inverter may be faulty and is feeding a back voltage to the generator
 
the genset is rated at 15 kw its single phase 240 volts 50 hz rpm 1500 when under load , the parameters set in the solar inverter limit to 25 amps draw from the genset, the overvoltage occurs at genset only when under load, charging the 24 off 2 volt batteries through the inverter.
if i open the circuit breaker at the genset the readout at the genset stays at the high voltage until i adjust the avr
this why i suspected the avr was faulty and replaced it
i think the solar inverter may be faulty and is feeding a back voltage to the generator
Well AVR should be in "AUTO " MODE REGULATING Generator output Voltage, is that the case at your site?

Otherwise you mentionned a potential failure of the Inverter ( That can be possible )

If you can make a run and share trends and datas as mentionned before that could be good to check ...
 
Tonka...
You mentioned large Capacitors. They don't show up in the drawing. When an AC generator is connected to a large capacitance load its terminal voltage exceeds that provided by its own excitation. Can you you see a sneak path that wasn't there when the system worked well?
Phil
 
Leroy-Somer-R250-AVR-922-197.jpgthis is the avr you can tune it at the volt pot, the capacitors in the digital phase convertor were isolated when the overvoltage occurs
i live in south australia 9 hours drive away from the generators agent, they cant help. my next step is SMA can do a remote check on the system through an agent who will connect a modem to the inverter, i have booked that for next week, thank you for your time and replies
 
View attachment 3056this is the avr you can tune it at the volt pot, the capacitors in the digital phase convertor were isolated when the overvoltage occurs
i live in south australia 9 hours drive away from the generators agent, they cant help. my next step is SMA can do a remote check on the system through an agent who will connect a modem to the inverter, i have booked that for next week, thank you for your time and replies
Thank you for the update...
Can you provide model/name of the Leroy Somer AVR

AVR should be in AUTO mode for regulating Voltage
 
the Leroy Somer AVR is R250, if you look at the picture there is a small potentiometer marked volt, that can be tuned to the voltage required, it should hold that volts automatically
 
thank you for your reply
I can only tell you that the generator starts the inverter reacts with an orange light to show its getting current from the genset, there is a period of a minute or so orange light turns green, then the inverter slowly builds the load on the generator and stays constant , sharing the load between the batteries and the house grid.
The load on the generator only decreases when the batteries get to 85%
the genset head is a Leroy Somer LL1014 i am searching now to see if i can find information on the diode kit
 
Update, took generator to Meccalte dealer, he was willing to test with load this is the report

Generator takes load, voltage is stable BUT fuel system is dirty and causes engine speed to fall below 50hz. picture above is only at half rated load and engine speed is falling down considerably. genset should be capable of producing 50Amps at 50hz. fuel bulb being cleaned, new fuel filter fitted and strainer on fuel pump being cleaned too. also found lose connection on main output circuit breaker, which is also your AC voltage measurement back to the controller, explains erratic voltage displays and nuisance tripping. found excitation system of alternator with very low resistance, due to moisture ingress, that has been dried out and now is ok. will have genset running again in an hour or so, for another full load test. will advise outcome later

runs much better now with clean filters. new electric fuel pump and pre filter (protecting the fuel pump) fitted. you do need to clean out the fuel tank, it's contaminated with water. replaced the current transformer, now LCD reads the load correctly. maximum load we can achieve is 40amps at 50hz. above picture the frequency is dropping below 50hz as load increases. currently on load test for an hr, all appears OK.
 
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